Electronic devices are becoming increasingly widespread. At the same time, these can be produced in ever more compact forms. In such miniaturized devices, for example in those which are carried by the user over relatively long periods of time or permanently (such as hearing aids, insulin pumps or other medication dispensers etc.), it is important for the battery for supplying power to likewise be as compact and lightweight as possible while at the same time also being powerful.
Rechargeable batteries with standard shapes and a metal housing are conventionally used for such devices. These rechargeable batteries are inserted directly or as a potential-free packet with an integrated protective circuit into an opening in the device which is intended for it. The space required for a rechargeable battery and a rechargeable battery compartment and the weight of the metal housing of the rechargeable battery restrict the design for various applications.
High energy densities can be achieved with wound batteries, as described, for example, in EP 0 144 757 (GTE Government Systems) or U.S. Pat. No. 5,556,722 (Sanyo). A winding (“jelly roll”) with an active cathode strip and an active anode strip is accommodated in a sealed housing. The common helically wound strips are electrically separated by a separator, with a liquid electrolyte or a polymer serving as the ion conductor. Electrical conductors connect the strips to current connections (negative and positive poles of the battery) which are arranged on the outside of the housing.
EP 1 100 138 A1 (Wyon AG) discloses a wound battery which has a space-saving design and therefore permits a high capacity together with a low space requirement. In this case, the current connection is formed by small tubes which project into the housing and at the same time serve as supports for the electrode winding which is impregnated with electrolyte.
EP 1 398 841 A1 (Wyon AG) discloses a further wound battery which has a screw-connected, gas-tight contact bushing. This design is compact, it is additionally particularly well-suited to rechargeable batteries with plastic housings which can be produced with a lower weight than conventional rechargeable batteries with metal housings.